Test per-flow priority and priority set by firewall (pf) .
em0 <---> igc0
Capture packets on igc0
```
# ifconfig igc0 up
# tcpdump -nevi igc0
```
Setup
```
# ifconfig em0 -vlanhwtag -pcp
# ifconfig em0 inet 192.0.2.1/24
# arp -s 192.0.2.2 0:1:2:3:4:5
```
Test per-flow priority
```
# ping -c1 -C3 192.0.2.2
```
Test priority set by firewall (pf) .
```
# echo "pass out proto icmp set prio 5" > /tmp/pf.conf
# kldload pf
# pfctl -f /tmp/pf.conf
# pfctl -e
pf enabled
# sysctl net.link.vlan.mtag_pcp=1
net.link.vlan.mtag_pcp: 0 -> 1
# ping -c1 192.0.2.2
```